@mosspaAs far as the LD50 of nicotine is concerned, i believe you may find this interesting:
How much nicotine kills a human? Tracing back the generally accepted lethal dose to dubious self-experiments in the nineteenth century
Authors blog: Electronic cigarettes and nicotine poisoning
Yes, I did find that interesting, but not too surprising. It's amazing how much of this is prevalent in the modern scientific literature. The problem is largely because of the laziness of the scientists. Quite often, you will find the primary reference to a "fact" being a source, like an ancient textbook, that is actually a secondary reference with no primary reference given. In general scientific writing, any "statement of fact" should be followed by a citation to the reference for the "fact". It is far easier to mention a textbook and hide the reference in the 100s that appear in the reference section than it is to actually find the primary reference. Editors have better things to do with their time then determine the veracity of every citation/reference combo. That is how many accepted "facts" become accepted "facts".
I believe that the myth surrounding nicotine addiction is based on this same sort of error. By using "nicotine" synonymously with "tobacco", scientists who should know better, have allowed the propagation of the myth. Undoubtedly, the 'primary reference' would be a statement of a property attributed to "nicotine" that was actually a property of "tobacco".